Maximal activation of the human diaphragm but not inspiratory intercostal muscles during static inspiratory efforts.
It is widely held that transdiaphragmatic pressure is a reliable index of the extent of central activation of the diaphragm but the maximal voluntary transdiaphragmatic pressure is lower during inspiratory than expulsive efforts. To determine whether the diaphragm is fully activated during the two manoeuvres supramaximal stimuli were delivered to both phrenic nerves during maximal efforts. No discernible twitch was evoked during 30-55% of attempted maximal efforts with either voluntary manoeuvre. Thus the difference in maximal transdiaphragmatic pressure between the manoeuvres must reflect changes in chest-wall geometry or mechanics rather than in the phrenic motor outflow. Inspiratory intercostal muscle activity was consistently submaximal during maximal inspiratory efforts.
Duke Scholars
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Related Subject Headings
- Positive-Pressure Respiration
- Phrenic Nerve
- Male
- Intermittent Positive-Pressure Breathing
- Intercostal Muscles
- Humans
- Female
- Electric Stimulation
- Diaphragm
- 5202 Biological psychology
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Positive-Pressure Respiration
- Phrenic Nerve
- Male
- Intermittent Positive-Pressure Breathing
- Intercostal Muscles
- Humans
- Female
- Electric Stimulation
- Diaphragm
- 5202 Biological psychology